In the context of global carbon neutrality goals and energy transformation,it is urgent to develop new technologies that efficiently convert CO2 into renewable energy carriers such as CH4. Microbial electrolysis cells (MECs), which couple electrochemistry with microbial metabolism for CO₂ conversion, exhibit performance that is heavily dependent on the electron transfer capabilities and biocompatibility of the cathode.Therefore,Nafion was employed to load nanoscale Fe3O4 and carboxylated multi-walled carbon nanotubes onto nickel foam (NF). The electrochemical performance of the modified NF was characterized using techniques such as electrochemical impedance spectroscopy (EIS),cyclic voltammetry (CV),and linear sweep voltammetry (LSV). The results indicated that the modified NF exhibited lower internal resistance,a larger electrochemical active surface area,and enhanced hydrogen evolution capabilities.Ultimately,this modified cathode was employed in a constant current dual-chamber anaerobic methanogenic MECs for the electrochemical reduction of CO2 to CH4.The results demonstrated that under a constant current of -0.1 A,the CH4 concentration of the nanoscale Fe3O4 and carboxylated multi-walled carbon nanotube-modified NF group could reach 90%,surpassing the 80% CH4 concentration of the NF group. Moreover,the daily CH4 production of the modified group was 295 mL,higher than the 260 mL daily methane production of the NF group,reflecting an increase of 13%. It was found that the modified NF exhibited higher hydrogen production and lower internal resistance, creating a more favorable environment for the growth and enrichment of hydrogenotrophic methanogens, thereby facilitating the electrochemical reduction of CO2 to CH4. Subsequent microbial community analysis also indicated that the relative abundance of the hydrogenotrophic methanogen Methanobacterium in the reactor with the modified NF was higher than that in the NF group,further facilitating the process of H2 serving as an electron donor for CO2 reduction to CH4. This research provides new ideas and experimental evidence for the development of novel non-precious metal composite cathode materials in bioelectrochemical systems.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |